Apparatus for making plastic articles

ABSTRACT

Disclosed is a method and apparatus for forming multi-directionally oriented plastic articles by accumulating a body of plasticized thermoplastic material in an amount at least sufficient to form the desired article, and advancing the material under pressure from said body forward and through an orifice. The material is non-linearly sheared while being advanced from the body toward the orifice and prior to its issuance from the orifice to induce orientation stresses into the material, and during shearing the material is at a temperature which is conducive to orientation. The orientation stresses are frozen into the material when the material is formed to a desired configuration exteriorly of the orifice by known plastic forming techniques, such as extrusion, blow molding, injection molding, compression molding, thermoforming and the like. During such forming, additional orientation stresses may be induced in the material and superimposed upon those stresses previously introduced thereinto.

This is a division of application Ser. No. 164,664, filed June 30, 1980,now U.S. Pat. No. 4,323,340, which is a division of Ser. No. 854,555,filed Nov. 25, 1977, now U.S. Pat. No. 4,305,902, which is acontinuation of Ser. No. 670,936, filed Mar. 26, 1976, now abandoned,which is a continuation of Ser. No. 461,361, filed Apr. 16, 1974, nowabandoned.

BACKGROUND OF INVENTION

It has long been known that thermoplastic materials may be "oriented",i.e., the molecules of the material are oriented or aligned and thenfrozen into their aligned relationship. Such orientation increases thephysical properties of the material in the direction of orientation.

For example, in "stretch oriented" filaments, an extruded strand isstretched axially, and the tensile strength of the strand is increasedby several orders of magnitude related to the amount of stretching.Similarly, sheet material can be "bi-axially oriented" by stretching thesheet longitudinally and transversely. The physical strength of such abi-axially oriented sheet is again increased by several orders ofmagnitude. In a similar manner, blow molded articles can be"multi-directionally oriented" by simply blowing the material into afinal article, the stretching of the parison or pre-form upon blowing tothe final shape accomplishing the orientation. In a blown article, thephysical properties are increased upon orientation, and the greaterresistance of the wall to the transmission of vapor there through isalso known to be a consequence of multi-directional orientation.

In order to accomplish orientation in thermoplastic articles bypresently known techniques, the material must be stretched while it isat a temperature conducive to orientation, i.e., a temperature at whichthe molecules are sufficiently mobile to be oriented and yet are not somobile as to immediately lose the orientation which has been inducedtherein. Some orientation is necessarily included into any thermoplasticmaterial as it is issued from an orifice, as in normal extrusion orinjection molding operations, but the material is linearly oriented inthe direction of flow only, and the material is at such an elevatedtemperature that the orientation is dissipated by random rearrangementsof the thermally active molecules. It has been determined that thethermal decay of orientation is inversely proportional to thetemperature of the materials at the time the orientation stress isinduced. In other words, at normal extrusion temperatures, on the orderof 400° F., the orientation induced during flow through the orifice isdissipated by molecular rearrangement in an extremely short period oftime, usually on the order of 0.1 seconds.

As a result, present orientation procedures are carried out after thethermoplastic material has issued from the orifice and has been cooledexteriorly of the orifice to a temperature at which the molecules areless mobile and the orientation dissipation times are greatly increased.For example, in stretch orientation, the extruded material is cooled ina water bath and then reheated in a "orienting oven" to a temperaturesubstantially less than extrusion temperature, and the extruded, chilledand reheated strand is then stretched. In blow molding, an injectionmolded parison is chilled in the open air after injection and is thenblown. Alternatively, an extruded parison is chilled to a rigid stateand then reheated to a temperature substantially less than extrusiontemperature, so that orientation can be obtained during blowing at thelower temperature. Orientation is normally not accomplished in injectionmolding, since the material is injected into he mold at or near its melttemperature, at which temperature any orientation obtained at theorifice is dissipated before the mold filling and chilling operation iscomplete.

BRIEF DESCRIPTION OF THE INVENTION

The present invention now proposes a method of and apparatus for formingmulti-directionally oriented plastic articles in a more effective andmore efficient manner by inducing orientation in a thermoplasticmaterial as it issues from an initial forming orifice and without any ofthe additional, repetitive, post-orifice operations required by theprior art.

Generally, the present invention contemplates the issuing ofthermoplastic material in a plasticized state from an initial orificewith orientation strains induced into the material and with the materialat a temperature conducive to orientation, so that further processing ofthe material immediately exterior to the orifice will produce amulti-directionally oriented article. The elimination of post-orificecooling or chilling and reheating steps substantially speeds up theforming cycle for such oriented articles, and it is simply necessary tocarry out the normal plastic forming techniques, such as extrusionchilling, blow molding, injection molding, compression molding,thermoforming, or the like upon the already-oriented material issuingfrom the orifice. The economy due to faster cycle times, the eliminationof cooling or reheating operations, and the simplification of theforming apparatus will be readily appreciated. Further, it is possibleto superimpose additional orientation stresses on those already presentin the material issuing from the orifice, thereby obtaining articles ofenhanced physical properties over those previously known.

Generally, the thermoplastic material is plasticized and accumulated ina body adjacent an orifice, the body being cooled or tested to atemperature such that it is a temperature conducive to orientation asthe material issues from the orifice. The material is expressed underpressure from the accumulated body to and through an orifice. As thematerial travels to the orifice, it is non-linearly sheared, preferablyrepeatedly, to induce orientation stresses into the material. As thematerial is sheared, its temperature may rise to a greater or lesserextent. The temperature at which the body of material is accumulatedprior to shearing is adjusted to that, during shearing, the material isat a temperature most conductive to orientation.

The forces necessary to shear the material may be generated by thepressure at which the accumulated material is expressed from theaccumulated body, i.e., the material may simply flow through alabyrinthian passage defined by alternate restrictive and relativelyopen areas, or the shear forces may be generated externally, as byrotation of one of the orifice-defining elements. In either event, theshearing is "non-linear", i.e., not simply axial to the direction offlow through the orifice.

As the sheared, highly stressed material issues from the orifice, it isimmediately further processed by known plastic forming techniques to afinished, multi-directionally oriented article.

The apparatus of this invention includes an accumulator for receivingplasticized material from a conventional plasticizer of any desiredtype, means for controlling the temperature of material stored in theaccumulator, and means for expressing material from the accumulatorunder pressure. Since the flow viscosity of plasticized material atorientation temperature is much greater than at normal plasticizingtemperatures, the power discharge of the accumulator is necessary.

The orifice through which accumulator discharge occurs is theorientation orifice. This orientation orifice can take several forms,but in essence, the orifice configuration is calculated and designed togenerate repeated, non-linear shearing forces in the material flowingthrough the orifice. Several different orifice configurations aredisclosed herein.

The specific post-orifice processing apparatus forms no part of thisinvention, so long as the processing is carried out promptly andeffectively before the orifice-induced orientation decays. Severaldifferent types of such processing apparatus are proposed, ranging froma simple chilling of an extrusion, to blow molding, to injectionmolding. Any other desired type of processing apparatus may be used asdesired.

OBJECTS

It is, therefore, an important object of the present invention toprovide a method of an apparatus for forming oriented plastic articlesby expressing plasticized thermo-plastic material through an orifice andshearing the material in a non-linear shear pattern while the materialis at a temperature conducive to orientation, the material being chilledand set by conventional plastic forming operations performed exterior tothe orifice and performed prior to thermal decay of themulti-directional orientation induced in the material during theshearing step.

Another important object of this invention is the provision of a methodof and apparatus for forming oriented plastic articles by accumulating abody of plasticized thermo-plastic material adjacent an orifice and at atemperature not greater than that temperature which is conducive toorientation, and expressing the material from the body through anorifice while shearing the material in a non-linear shear pattern toeffect multi-directional orientation in the material issuing from theorifice.

It is a further important object of this invention to provide a methodof and apparatus for making a plastic article by providing plasticizedthermo-plastic material at a temperature conducive to orientation of thematerial and displacing the material through an orifice while repeatedlyand progressively non-linearly shearing the material tomulti-directionally orient the material, and then further processing thematerial exteriorally of the orifice while the material is stilloriented as the result of the shearing operation.

It is yet another, and no less important, object of this invention toprovide a method and apparatus for the formation of oriented plasticarticles by plasticizing thermo-plastic material at a normalplasticizing temperature, segregating a body of the plasticizedmaterial, chilling the accumulated body of material to a temperature nogreater than a temperature conducive to orientation of material, issuingmaterial from the body while shearing the material in a non-linear shearpattern to multi-directionally orient the material, and chilling theoriented material immediately after the shearing operation and prior toappreciable thermal decay of the orientation thereof.

Other and further objects of the present invention will become readilyapparent from the appended disclosure and claims.

ON THE DRAWINGS

FIG. 1 is a schematic representation of a blow molding machineincorporating the method and apparatus of the present invention;

FIG. 2 is an enlarged, fragmentary, sectional view of a portion of theapparatus of FIG. 1 in an initial or starting operation of a blowmolding cycle;

FIG. 3 is a view similar to FIG. 2 illustrating the apparatus of FIG. 1during the performance of a blow molding cycle;

FIG. 4 is an enlarged view of the orifice design of the blow moldmachine of FIGS. 1 through 3;

FIG. 5 is a fragmentary, elevational, somewhat schematic view of aninjection molding apparatus of the present invention capable of carryingout the present invention, the apparatus being shown prior to theinitiation of an injection molding cycle;

FIG. 6 is a view similar to FIG. 5 showing the apparatus carrying out aninjection molding cycle;

FIG. 7 is a view similar to FIG. 5 but illustrating the apparatus at thecompletion of an injection molding cycle;

FIG. 8 is a fragmentary view, with parts broken away and in section, ofan apparatus generally similar to that of FIGS. 1-4 but utilizing adifferent orifice design for the issuance of a tubular extrusion for usein blow molding or the like operations;

FIG. 9 is a fragmentary view, with parts broken away and in section,similar to FIG. 8, illustrating yet another orifice design of thepresent invention;

FIG. 10 is a fragmentary sectional view, of a different orifice designof the present invention;

FIGS. 11 and 12 are fragmentary views of the mandrel tip and the orificeplate, respectfully, of the orifice design of FIG. 10;

FIG. 13 is a fragmentary, sectional view of an orifice design similar tothat of FIGS. 8 and 9;

FIG. 14 is a view of the mandrel tip alone of the design of FIG. 14;

FIG. 15 is a view of the orifice arrangement alone of FIG. 13; and

FIG. 16 is a sectional view taken along the plane 16--16 of FIG. 13.

AS SHOWN ON THE DRAWINGS

In FIGS. 1-4, reference numeral 20 refers generally to an articleforming apparatus of the present invention, in this particular instancea blow molding machine. This blow molding machine comprises areciprocating screw extruder 21 of conventional type and receivingpelletized thermoplastic material, such as PVC, polyethylene,polypropylene or the like, from an overhead supply hopper 22.

The machine includes a vertically extending accumulator 23, hereinafterdescribed in greater detail, from which a freely pendant tubular parison24 issues downwardly. A support table 25 underlying the parison 24carries an upstanding blow pipe 26 fixed to the table and connected to asource of air or other blowing medium under pressure. A pair of blowmold sections 27 cooperatively define an interior mold cavity 28conforming to the shape to be formed. These blow mold sections 27 areopened and closed by actuating cylinders 29 movable with the table 25and supported therefrom. The table itself, together with the blow moldsections 27 and the blow pipe 26 is elevated and lowered by verticallydisposed actuating cylinders 30.

This type of blow molding machine is quite well known in the art. Thedetails of the blow molding machine per se form no part of the presentinvention.

As best shown in FIG. 2, the extruder 21 includes a reciprocating screw32 which advances plasticized material toward an extruder outlet opening33. Secured to the mounting flange 34 is the accumulator indicatedgenerally at 23. An accumulator block 35 has a vertically disposed,cylindrical bore 36 closed at its lower end by an orifice block 37having a vertical orifice bore 38 opening onto the accumulator chamberdefined by the vertical bore 36. The upper surface of the orifice block37 is chamfered, as at 39, to define an upper valve seat surrounding theorifice opening 38 at its accumulation chamber end, as will behereinafter more fully described.

The accumulator chamber 40 defined by the opening 36 communicates withthe outlet opening 33 of the extruder through a reduced bore 41, anenlarged check valve bore 42 and a check valve body 43. A spherical ballcheck 45 is confined in the chamber 42 between the reduced opening 41and the limit pin 46 carried by the check valve body 43. The function ofthe check valve ball 45 is quite simple. When the pressure in theextruder 32 exceeds that in the chamber 40, the check valve restsagainst the pin 46, accommodating the flow of plasticized material fromthe extruder into the accumulator chamber 40. When the pressure in theaccumulator chamber exceeds that of the extruder 32, the ball check 45closes the opening 41 preventing communication, as best shown in FIG. 3.

Disposed within the accumulator chamber 40 is an accumulator piston 50.This accumulator piston 50 is tubular and projects upwardly beyond theconfines of the accumulator chamber 50 to bear at its upper end anenlarged piston head 51 having a peripheral seal 52 confined in anactuating cylinder 53, this cylinder 53 surmounting the accumulator body35. The cylinder 53 receives hydraulic equipment from a source of suchliquid under pressure (not shown) through upper supply line 54 and thelower supply line 55. The accumulator piston 50 has an axially extendingslot 56 in its outer periphery to accommodate the check valve body 43which projects slightly radially into the chamber 40.

Telescopically received within the bore of the tubular accumulatorpiston 50 is a tubular valve guide 60 which is secured against axialdisplacement by a spider (not shown) carried by the accumulator body 35.This valve guide 60 is provided with a downwardly opening cylindricalrecess 61 forming a stop shoulder 62 where the recess intersects thebore of the tubular valve guide 60. Positioned in the recess for axialsliding motion therein is a cylindrical valve body 65 which isconstantly urged downwardly in the recess 61 by a compression spring 66confined between the upper surface of the valve body 65 and a threadedcap 67 secured to the upper end of the valve body 60.

The lower end of the valve body 65 is provided with reduced cylindricalextension 68 joined to the remainder of the valve body 65 by a chamferedactuating face 69 projecting axially from the extension 68. Extendinginto the lower orifice opening 38 is an orifice mandrel 70 joined to orintegrally formed with the valve body extension 68 through a chamferedvalving face 71 which sealingly engages the chamfered upper face 39 ofthe orifice plate 37 when the valve body 65 is normally urged downwardlyto its lowermost position by the compression spring 66.

As best shown in FIG. 4 of the drawings, the orifice mandrel 70 isprovided with a series of axially spaced, separate, annular, peripheralrib 72 which project radially from the orifice mandrel 70 toward theorifice bore 38. Similarly, the orifice bore 38 is provided with aplurality of radially inwardly projecting, annular peripheralprotuberances 73 which project inwardly toward the mandrel extension 70.

The operation of the device of FIGS. 1 through 4 will be apparent from acomparison of FIGS. 2 and 3. In FIG. 2, plasticized material from theextruder screw 32 passes through the extruder opening 33 and the passage41 past the ball check valve 45 into the annular accumulator chamber 40defined between the accumulator block bore 36 and the exterior surfaceof the valve guide 60. Fluid under pressure through the hydrauliccylinder line 55 has previously raised the piston 51. The force of thespring 66 is great enough to retain valve body 65 seated, i.e., with thechamfered valve face 71 contacting the valving surface 39 of the orificeblock 37, despite the fact that the actuating face 69 of the valve body65 is exposed to the pressure of the plasticized material from theextruder.

Thus, when the accumulator is in its condition of FIG. 2, no plasticizedmaterial is being dispensed from the accumulator. Further, heat exchangefluid is circulated through the coolant passages 75. Generally, thiscoolant will be a chilling medium to reduce the temperature of theplasticized material filling the accumulator chamber from the melttemperature of the plasticized material to a temperature which isconducive to orientation of the plasticized material.

Those temperatures which are conducive to orientation in thermoplasticmaterials vary with the specific material. The average temperature foreach essentially crystalline polymer lies intermediate the crystallinemelting point of the material plus 20° F. and the crystalline freezingpoint of the material less 20° F. With respect to essentially amorphouspolymer, such as polyvinyl chloride and polystyrene, the glasstransition temperature is utilized, rather than crystalline melting andfreezing temperatures. For high density polyethylene (having a densitylying between 0.954 and 0.970) it is preferable to operate at atemperature of 250° F. plus or minus 20° F. For polyvinyl chloride theideal orienting temperature is 205° F. plus or minus 25° F., and forpolystyrene 266° F. plus or minus 10° F., for polypropylene, the idealtemperature is 275° F. plus or minus 10° F.

When it is desired to express material from the accumulator and with theaccumulator in its condition of FIG. 2, fluid is introduced thruhydraulic line 54 into the cylinder 53 to displace the piston 52downwardly, toward its FIG. 3 position. The first displacement of thepiston 51 will, of course, increase the pressure in the accumulatorspace 40. This increase in pressure will (1) displace the ball checkvalve 45 to the left to prevent the flow of material from the chamber 40into the extruder 32, and at the same time (2) react against theactuating surface 69 of the valve body 65 to displace the valve body 65upwardly against the compression spring 66. This action opens theorifice to the accumulation chamber 40.

Further downward movement of the piston 50 will force material from theaccumulator chamber 40 through the orifice. The expression of materialthrough the orifice will subject the material to non-linear shearingforces, because the material must flow between the alternature, spacedprotuberances formed on the mandrel 70 and on the orifice bore surface38. As a result, the material flows through a tortuous flow path ofalternately restricted and enlarged size, so that the material isrepeatedly and progressively non-linearly sheared. The material isexpressed thru the orifice under substantial pressure, preferably inexcess of 20,000 psi.

Since the material is at a temperature conducive to orientation, thisshearing will cause the material to orient as it is expressed from theaccumulator space 40 through the orifice under the force of the rapidlymoving piston. The tubular parison 24 is thus rapidly issued from theorifice and between the open blow mold section 27 onto the blow pipe 26.Cylinders 29 are immediately actuated to enclose the parison, and theparison is immediately blown to its final configuration. The blowingoperation is carried out in a conventional manner well-known in theprior art. It appears unnecessary to describe the blowing operation indetail.

As above explained, time is of the essence, so that the orientationinduced in the parison during the repeated shearing at the orifice isnot thermally dissipated or degraded by the passage of time before thearticle is blown to its final configuration and the orientation isfrozen in. Of course, additional orientation will be obtained because ofthe inflation of the parison to the larger final article interiorally ofthe blow mold sections 27.

THE EMBODIMENT OF FIGS. 5-7

In that embodiment of the invention as illustrated in FIGS. 5-7, adifferent form of accumulator and orifice arrangement is utilized forinjection molding.

More specifically, the extruder 21 communicates with a support block 80having a vertical bore 81 therein and an enlarged counterbore 82defining a horizontal stop surface 83. Positioned in the bore 81 is adisplacement bushing, indicated generally at 85. This displacementbushing has a lower cylindrical portion 86 sealingly received in thebore 81 and terminating at a lower open end 87. The bushing 85 has anaxial bore 88 of stepped configuration diminishing generally upward fora purpose to be hereafter more fully explained.

The bushing carries a radially enlarged shoulder 89, the lower surfaceof which abuts the stop shoulder 83 of the block 80 when the bushing isfully displaced downwardly, as illustrated in FIG. 7. The upper surface90 of the shoulder 89 contacts the under surface of a threadedadjustment cap 91 when the bushing 85 is in its full upward position, asshown in FIG. 5. This adjustment cap 91 is annuler to receive the uppercylindrical end 92 of the bushing therethrough, and the cap 91 isthreaded to adjustable engage the threaded exterior upper surface of theblock 80.

Extending axially through the bore of the bushing 85 is a rotatable core100. This core 100 has a lower cylindrical portion 101 snugly receivedwithin the bore 81 of the block 80 and an upper, generally conical,stepped extension 102 projecting into the bore 88 of the bushing 85. Theexterior surface of the extension 102 is provided with a peripheral,spiral thread 103. The lower cylindrical portion of the core 100projects downwardly beyond the bore 81 of the block 80, as at 105, andthe exterior of this projection is provided with gear teeth 106 whichmesh with a spur gear 107 driven by a motor 108.

The core 100 is provided with an axial bore 110 projecting completelytherethrough and countersunk as at 111 to provide a horizontal stopshoulder 112 adjacent the lower extremity of the bore. Positioned withinthe bore 110 of the core 100 is a cylindrical mandrel 115, this mandrelbeing keyed to the core, as at 116, to be corotatable with the core 100and yet to be axially slidably displaceable with respect to the core100. The upper, cantilevered free end 117 of the mandrel 115 projectsbeyond the core 100 and is provided with a helical peripheral thread118.

The lower extremity of the mandrel 115 is provided with an enlarged head119 snugly guided within the counterbore 111 of the core 100. An end cap120 is seated in the counterbore 111 and provides a lower stop for thehead 119, and a compression spring 121 is confined within the cap 120 tobear against the undersurface of the head 119. The spring 121 normallyurges the mandrel upwardly to its position of FIG. 5, but accommodatesmovement of the mandrel downwardly to its position of FIG. 6 against theend cap 120.

The free upper end of the mandrel 115 sealingly fits into an orifice 122the bore 88 is cylindrical and threaded, as at 124. When the mandrel 115moves downwardly against the compression spring 121, the orifice 122 isopen, as illustrated in FIG. 6, and the orifice is in communication withan accumulation space between the displacement bushing bore 88 and theexterior surfaces of the core 100 and the mandrel 115.

The free upper extremity of the displacement bushing 85 is recessed, asat 123, to receive the lower end of a cylindrical mold 125 havingtherein an interior frusto conical recess 126 open at its lower end andcounterbored at its upper end to provide an enlagged lip recess 127. Anoverhead mold core 130 cooperates with the one-piece mold 125, this moldcore having a lower frusto conical plug portion 131 insertable into themold cavity 126 and an enlarged upper stop shoulder 132 abutable withthe upper surface of the mold 125 when the mold 125 and the mold core130 are assembled as illustrated in FIG. 6.

The mold core is actuated by a fly wheel 135 having a crank arm 136attached adjacent the periphery thereof, as at 137, and also attached asat 138, to an actuating ear 139 carried by the mold core and projectingabove the shoulder 132. Of course, both the mold 125 and the mold core130 are guided for vertical movement only by suitable guide means (notshown).

The operation of the device of FIGS. 5, 6 and 7, will be readilyapparent from a comparison of these Figures. The operation of theextruder has filled the accumulator space 140 between the bushing bore88 and the combined exterior surfaces of the displacement core 100 andthe mandrel 115 with plasticized material. A check valve 141 interposedbetween the extruder and the space 140 accommodates flow of the plasticfrom the extruder to the space, but not the reverse flow, in the mannerhereinbefore described in connection with the embodiments of FIGS. 1through 4.

The plastic material in the space 140 is appropriately cooled to atemperature which does not exceed that temperature at which theplasticized material is conductive to orientation, as above explained indetail. This cooling is accomplished by coolant passages 142 in thebushing 85 and coolant passages 143 in the displacement core 100.

Initially, the fly wheel 135 is actuated to lower the mold core 130until the shoulder 132 thereof abuts the upper surface of the mold 125.Then the mold core and the mold are jointly lowered into the recess 123in the bushing 85. The fly wheel is further actuated to displace themold 125 and the core 130 downwardly, jointly with the bushing 100. Thismovement of the bushing is accommodated by the space between the stopsurfaces 83 and 90, and the extent of this displacement can be varied bythreadedly adjusting the cap 91 on the peripheral threads on the block80.

The displacement of the bushing 85 downwardly reduces the volume of theaccumulator space 140, thereby increasing the pressure of theplasticized material in the space 140. This increase in pressure seatsthe ball check valve 141 as illustrated in FIG. 6, and this increase inpressure also displaces the mandrel 115 downwardly within thedisplacement core 100. For this purpose, the mandrel 115 is providedwith an upwardly facing, radial shoulder 145 defined at the intersectionof the body of the mandrel 115 and the reduced upper threaded extremity117 thereof. The area of the shoulder 145 is balanced against thecompressive force of the spring 121, so that the mandrel normallyoccupies its position of FIG. 5 when the accumulator space 140 is filledunder the pressure of the extruder 21. However, upon an increase inpressure, the biasing force of the pressure exerted on the shoulder 145will exceed the compression force of the spring 121, and the mandrelwill move downwardly from its position of FIG. 5 to its position of FIG.6.

The downward mandrel movement first opens the orifice 122. Continueddownward movement of the core 130, the mold 125 and the bushing 85 willfurther reduce the size of the accumulator space 140, and plasticmaterial will be displaced from the space 140 into the mold cavitycooperatively defined by the mold core 130 and the mold 125. Thematerial in the space 140 must flow upwardly over the helical grooves103 in the displacement core 100 and also over the helical thread 118formed on the mandrel tip 117. Additionally, the upper portion of thebore 88 in the bushing 85 is contoured at 124 with a helical thread ofopposite hand to that on the mandrel tip. The rotation of the core 100and the mandrel 115 by the motor 108 and the gears 107, 106 togetherwith the helical surfaces subjects material flowing between the surfacesto repeated and progressive non-linear shearing action. As a result, thematerial issuing from the orifice 122 and displaced into the mold cavitywill be multi-directionally oriented.

When the fly wheel 135 reaches its lowest point, the volume of theaccumulator space 140 is at a minimum, and the pressure within the space140 will be at its maximum. Further rotation of the fly wheel will raisethe core 130 back toward its original position of FIG. 5 and willaccommodate the return of the bushing to its original position of FIG.5. In FIG. 7, the bushing 85 is illustrated at its lowest position,i.e., against the stop 83, and the volume of the space 140 is at aminimum. Since the fly wheel is no longer forcing the bushing 85downwardly, there is no pressure in the space 140 except that pressureexerted by the extruder 21. The extruder pressure has unseated the ballcheck 141, and material is beginning to flow from the extruder into thespace 140 to refill the accumulator. Under these circumstances, themandrel 115 closes the orifice 122 under the pressure of the spring 121,and the continued flow of plasticized material from the extruderelevates the bushing 85 and the mandrel 115 upwardly to their originalpositions of FIG. 5.

The article 146 which is formed in the mold space provided between thecore 130 and the mold 125 has been injection molded with orientedmaterial while the material is at a temperature conducive to orientationobviously, the article 146 may be subsequently blow molded or otherwisefurther processed as desired.

THE EMBODIMENT OF FIGS. 8 and 9

In FIG. 8, an accumulation system similar to that of the embodiments of1-4 is utilized, and identical reference numerals refer to identicalelements of this accumulator system.

In the embodiment of FIG. 8, plasticized material at a temperatureconducive to orientation of the material is expressed through theaccumulator discharge port 38 corresponding to the orifice 38 heretoforedescribed, but of cylindrical form. The plasticized material 150 passesinto an orifice block 151 having a horizontal inlet opening 152 alignedwith the discharge orifice 38, and opening onto a vertical cylindricalpassage 153 having a conical, downwardly opening orifice passage 154.

Positioned in this conical orifice opening 154 is a conical, rotatablemandrel indicated generally at 155 and comprising a conical head 156somewhat smaller than the orifice 154 and defining therewith a conicaldischarge opening 157. The mandrel includes a stem portion 158projecting vertically through the block 151 and journalled for rotationin the bearing 159. A drive motor 160 rotates the mandrel 155.

The plasticized material displaced by the accumulator through theopening 152 and flowing through the conical mandrel 157 is repeatedlysheared at its interior surface by the rotatable mandrel stem 158 andthe rotatable conical mandrel tip 156, so that the tubular extrusion 161is multi-axially oriented.

The tubular extrusion 161 can be utilized as a parison for a blowmolding operation carried out as in FIGS. 1 through 4, or the tubularextrusion 161 can be simply chilled in its tubular shape, or tubularextrusion 161 as oriented can be utilized for any other purpose desired.

A different form of tubular extruder is illustrated in FIG. 9 of thedrawings. Here, the orifice block 151 again receives plasticizedmaterial 165 from the accumulator 35, the material 165 flowing through ahorizontal passage 166 communicating with a cylindrical vertical passage167 provided with annular internally facing ribs 168. A vertical mandrel170 of cylindrical form is provided with radially projecting annularprotuberances 171, the mandrel 170 being journalled by a bearing 172 anddriven by a motor 173.

The plastic material 165 expressed through the extrusion nozzle 151 ofFIG. 9 is subjected to rotary shearing motion by virtue of the rotationof the mandrel 170, and at the same time the material is further shearedby being forced to flow over the successive annular protuberances 168,171. This combination of shearing forces exerted on the material 165forms a tubular extrusion 175 which again is multi-directionallyoriented. Again, the tubing can be used for any desired purpose, asheretofore explained.

THE EMBODIMENTS OF FIGS. 10-12

In FIGS. 10-12, another shearing orifice arrangement is illustrated. Itis understood that this shearing orifice arrangement receivesplasticized material 177 at a temperature conducive to orientation froma source, for example, from the accumulator arrangement 35 alreadydescribed in connection with previous embodiments of the invention.

The embodiment of FIG. 10 includes an upper structural element 178having a cylindrical passage 179 therethrough, a second structuralelement 180 having a cylindrical opening 181 therein provided with ahelical thread 182 best illustrated in FIG. 12, the opening 181 beingjoined to the passage 179 by conical joining portion 183. Th orificeblock 185 underlies the element 180, this block having a cylindricalorifice passage 186 joined to the passage 181 by a conical joiningportion 187. Projecting through the aligned openings 179, 181, 186, is amandrel 190 comprising an upper cylindrical portion 191, a conicaljoining portion 192, a cylindrical extension 193 provided with threads194, a lower conical joining portion 196 and a cylindrical mandrel tip197 projecting axially through the passage 186. It will be noted thatthe threads 182 in the passage 181 and threads 194 of the mandrelportion 193 are of opposite hand.

The mandrel 190 may be utilized as the mandrel 65 of the accumulatorsystem of the embodiment of FIGS. 1-4, or, alternatively, the mandrel190 may be utilized as the mandrel of FIGS. 8 and 9. In either case, themandrel 190 may be driven for rotation by suitable means, or the mandrelmay be fixed against rotation.

In either event, plasticized material 177 displaced through the orificeblock and mandrel configuration of FIGS. 9 through 12 issues as atubular extrusion 198 which is oriented by the repeated shearing actioncaused by flow of the plasticized material through the tortuous,labrynthian passage defined between the threads 194, 182. In the eventthat the mandrel 190 is utilized as the equivalent of the valving member65 of the embodiment of FIGS. 1-4, the conical portion 192 or theconical portion 196 may be utilized as a valving element in combinationwith the appropriate conical surface 183, 187, respectively.

THE EMBODIMENT OF FIGS. 13-16

FIGS. 13-16 illustrate another orifice configuration forming a part ofthe present invention and capable of carrying out the method of thepresent invention.

Once again, the orifice structure includes an upper block 200 having acylindrical passage 201 therethrough, a mandrel block 202 having aninsert 203 supported therein. This insert 203 comprises a cylindricalinner surface 204 provided with axially extending spiral ribs 205 of aconfiguration best illustrated in FIGS. 15 and 16.

The ribs 205 are generally axially extending, but are not parallel tothe axis of the passage 204. The inclining of the ribs 205 withrespective to the axis of the bore gives the ribs a partial spiralconfiguration. The bore 204 communicates with the upper bore 201 throughan inclined conical joining portion 206. A lower outlet block 207 has acylindrical bore 208 joined to the upper bore 204 through a conicaljoining portion 209.

Disposed within the successive elements 200, 202, 203 and 207 is aunitary rotatable mandrel indicated generally at 210 and specificallyillustrated in FIG. 14. This mandrel includes an upper cylindricalportion 211, a conical transition portion 212 and a cylindricalorientation portion 213 provided with radially protruding, axiallydisposed ribs 214. A cylindrical mandrel tip 215 is joined to theorienting portion 213 by a conical joining portion 216. As indicated bythe directional arrow 220, the mandrel 210 is rotated by suitable means(not shown). Once again, the mandrel 210 may replace the valving elementand mandrel 65 in the embodiment of FIGS. 1-4 or, alternatively, themandrel configuration of FIGS. 13-16 may be utilized as the mandrels ofFIGS. 8 and 9.

In essence, the rotatable mandrel 210 cooperates with the ribbed passage204 to repeatedly and progressively shear plasticized material flowingthrough the mandrel structure. This repeated shearing again produces atubular extrusion which is multi-axially oriented and which may beutilized for any given purpose.

I claim:
 1. In an apparatus for making an oriented thermoplasticarticle, an accumulator for containing a body of thermoplastic materialof a volume at least sufficient to form the article, means for adjustingthe temperature of the body of said material while in said accumulatorto a temperature conducive to orientation, means defining an orifice,said accumulator being spaced from, and communicating with, said orificeby means defining a passageway, means for advancing material underpressure from said body in said accumulator toward and through saidorifice communicating with said accumulator via said passageway, meansin said passageway intermediate said accumulator and said orifice forshearing said material in a non-linear shear pattern tomulti-directionally orient the material prior to its issuance from saidorifice, and means for chilling said multi-directionally orientedmaterial exteriorly of said orifice to form an article in which thematerial is multi-directionally oriented.